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<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
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<body>
    <script>
        //num=0,max=10,每过一秒num++，当num>max清除定时器
        // clearInterval(name)
        var num = 0;
        var max=3;
        var timer;//定义一个定时器
        timer = setInterval(function(){
            if(num>max){
                clearInterval(timer);
            }else{
                alert(num)
                num++
            }
        },100) 
    </script>
</body>
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